I.C.E. equipped with means for maintaining reactor temperature about a single temperature

Abstract

A temperature sensor is disposed at the upstream or middle portion of a reactor for oxidizing the unburned constituents contained in the exhaust gases discharged from the combustion chambers of the engine. The air-fuel ratio of the air-fuel mixture supplied to the combustion chambers is controlled so as to maintain the temperature of the upstream or middle portion of the reactor at the predetermined level in the vicinity of but higher than the temperature corresponding to the critical point where the temperature of the downstream portion of the reactor begins to decrease.

What is claimed is: 
     
       1. A method of controlling the temperature in a reactor for oxidizing the unburned constituents contained in the exhaust gases discharged from an internal combustion engine, said reactor defining therein a reactor chamber including a first portion to which the exhaust gases from the engine are introduced, a second portion downstream of the first portion, and a third portion downstream of the second portion, through which third portion oxidized exhaust gases are discharged out of the reactor, said method comprising the steps of: sensing a temperature at a location including the first and second portions of the reactor, comparing the sensed temperature with a predetermined temperature which predetermined temperature is obtained when the temperature in the third portion of the reactor is within a first temperature range where the unburned constituents contained in the exhaust gases introduced from the combustion chamber of the engine are effectively thermally oxidized, said predetermined temperature being in close proximity to and higher than a temperature at said location which temperature is obtained immediately before the temperature in the third portion falls below the first temperature range;   supplying the combustion chamber of the engine with a first air-fuel mixture having a first air-fuel ratio which causes the temperature of the exhaust gases throughout the reactor to rise into the first temperature range, when the temperature of said location is below said predetermined temperature; and   supplying the combustion chamber of the engine with a second air-fuel mixture having a second air-fuel ratio which causes the temperature of the exhaust gases throughout the reactor to fall into a second temperature range where the unburned constituents contained in the exhaust gases are not oxidized, when the temperature of said location exceeds said predetermined temperature.   
     
     
       2. A method as claimed in claim 1, in which said predetermined temperature is below the temperature in the third portion which temperature is within said first temperature range. 
     
     
       3. An internal combustion engine comprising: means defining a combustion chamber;   air-fuel mixture supply means for supplying the combustion chamber with an air-fuel mixture;   a reactor disposed downstream of the combustion chamber for thermally oxidizing the unburned constituents contained in the exhaust gases discharged from the combustion chamber, said reactor including an elongate casing defining therein a reaction chamber, said reaction chamber including a first portion communicating with the combustion chamber, a second portion downstream of the first portion, and a third portion downstream of the second portion and communicating with the atmosphere to discharge oxidized exhaust gases out of the reactor;   temperature sensing means for sensing the temperature at a location including said first and second portions of the reaction chamber of said reactor;   means for causing said air-fuel supply means to supply a first air-fuel mixture having a first air-fuel ratio which causes the temperature of the exhaust gases throughout the reactor to rise into a first temperature range where the unburned constituents in the exhaust gases are thermally oxidized, when said temperature sensing means senses a temperature below a predetermined level, and to supply the air-fuel mixture having the second air-fuel ratio which causes the temperature of the exhaust gases throughout the reactor to fall into the second temperature range where the unburned constituents in the exhaust gases are not oxidized, when said temperature sensing means senses a temperature over the predetermined level, said predetermined level being obtained when the temperature in said third portion of said reactor is within the first temperature range, said predetermined level being in close proximity to and higher than a temperature at said location which temperature is obtained immediately before the temperature in the third portion falls below the first temperature range.   
     
     
       4. An internal combustion engine as claimed in claim 3, in which said predetermined temperature is below the temperature in the third portion which temperature is within said first temperature range. 
     
     
       5. An internal combustion engine as claimed in claim 3, in which air-fuel mixture supply means includes a carburetor comprising a throttle valve rotatably disposed within an air-fuel mixture induction passage thereof communicating with the combustion chamber, a venturi portion disposed upstream of said throttle valve, a main discharge nozzle opening to said venturi portion, a main well communicating through a main fuel passage with a float bowl of said carburetor and having a main air bleed for bleeding atmospheric air into said main well, said main discharge nozzle being connected to said main well, a low-speed circuit fuel passage communicating said main fuel passage with a slow port opening to the air-fuel mixture induction passage downstream of said venturi portion, said low-speed circuit fuel passage having a low-speed circuit air bleed for bleeding atmospheric air into said low-speed circuit fuel passage. 
     
     
       6. An internal combustion engine as claimed in claim 5, in which; said means for causing said air-fuel mixture supply and means includes a first auxiliary air bleed communicating with said main well for bleeding atmospheric air into said main well when opened, a secondary auxiliary air bleed communicating with said low-speed circuit fuel passage for bleeding atmospheric air into said low-speed circuit fuel passage when opened, a first electromagnetic valve disposed at said first auxiliary air bleed to open or close said first auxiliary air bleed and, a second electromagnetic valve disposed at said second auxiliary air bleed to open or close said auxiliary air bleed, said air-fuel mixture supply means supplying the first air-fuel mixture when said first and second auxiliary air bleeds are closed, whereas the second air fuel mixture when said first and second auxiliary air bleeds are opened. 
     
     
       7. An internal combustion engine as claimed in claim 6, in which said temperature sensing means includes a temperature sensor disposed at said location and arranged to generate an electric signal in response to the temperature in said location, and switch means electrically connected to said temperature sensor and in turn connected to said first and second electromagnetic valves of said air-fuel mixture supply means causing means, said switch means being arranged to cause said first and second electromagnetic valves to open said first and second auxiliary air bleeds, respectively, when receiving from said temperature sensor the electric signal representing the temperature over said predetermined level, whereas to cause said first and second electromagnetic valves to close said first and second auxiliary air bleeds, respectively, when receiving from said temperature sensor the electric signal representing the temperature below said predetermined level. 
     
     
       8. An internal combustion engine as claimed in claim 3, in which said combustion chamber defining means defines a plurality of combustion chambers. 
     
     
       9. An internal combustion engine as claimed in claim 8, in which the longitudinal axis of said elongate casing of said reactor is substantially parallel to the longitudinal axis of the cylinder block of the engine, said reactor having a plurality of inlets which are respectively parallelly connected to a plurality of exhaust ports which are respectively communicated with the plurality of combustion chamber, said inlets directly communicating with the first portion of the reaction chamber of said reactor. 
     
     
       10. An internal combustion engine as claimed in claim 9, in which said reactor includes a partition wall dividing said reaction chamber into a first chamber and a second chamber communicating with said first chamber, said first chamber forming part of said first portion of said reaction chamber. 
     
     
       11. An internal combustion engine as claimed in claim 9, in which said elongate casing of said reactor is in the form of cylinder and having first and second closed ends. 
     
     
       12. An internal combustion engine as claimed in claim 11, in which said reactor includes a cylindrical core defining thereinside a bore, coaxially disposed within said cylindrical casing spaced apart from the inner surface of the cylindrical portion of said casing, one end of said cylindrical core being secured to the inner surface of said first closed end of said cylindrical casing and the other end of said cylindrical core being spaced apart from the inner surface to said second closed end of said cylindrical casing to define outlet port means to communicate between the inside and the outside of said cylindrical core, said plurality of inlets opening to the inside of said cylindrical core for introducing the exhaust gases from the combustion chambers into the inside of said cylindrical core, making the inside of the cylindrical core said first portion of the reaction chamber, said outlet being located at the cylindrical portion of said cylindrical casing adjacent to said first closed end of said cylindrical casing. 
     
     
       13. An internal combustion engine as claimed in claim 11, in which said reactor includes a cylindrical core defining thereinside a bore, coaxially disposed within said cylindrical casing spacing apart from the inner surface of the cylindrical portion of said cylindrical casing, both ends of said cylindrical core being secured respectively to the inner surface of said first and second closed ends of said cylindrical casing, said cylindrical core having outlet port means formed through its wall adjacent to said second closed end of said casing to communicate between the inside and outside of said cylindrical core, said plurality of inlets opening to the inner side of said core for introducing the exhaust gases from the combustion chambers into the inner side of said core, making the inside of the cylindrical core said first portion of the reaction chamber, said outlet being located at the cylindrical portion of said casing adjacent to said first closed end of said casing.